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  1. Excellent work. We need to get on the game and counter the deniers before they even have time to think about the new findings. As Tamino said, let’s give them a little bit of the truth in their comments sections!!

    Comment by DrTskoul — 6 Dec 2011 @ 8:05 AM

  2. Guys,

    Don’t start your articles with a major grammatical error. We’re having enough difficulty with credibility without giving grounds for questioning literacy. I know it’s only a blog, but still….

    Dan Smith

    Comment by Dan Smith — 6 Dec 2011 @ 8:51 AM

  3. Curious. Don’t we all agree that temps have risen globally since the LIA? Why is this new study needed?

    Comment by Hardy Cross — 6 Dec 2011 @ 8:54 AM

  4. @1: The stock denier response is, “we never doubted that the world was warming, just what was causing it”. This is completely untrue of course, but that is their usual brush-off whenever someone refutes any of their nonsense claims about temperature records.

    Comment by JamesA — 6 Dec 2011 @ 8:56 AM

  5. “There are,” not “There is.”

    [Response: fixed – thanks. – gavin]

    Comment by climatehawk1 — 6 Dec 2011 @ 9:13 AM

  6. I’m scared to death of the next El Niño.

    Comment by Sphaerica (Bob) — 6 Dec 2011 @ 9:20 AM

  7. Can one plot the temperatures at the La Nina maxima for a long time? This would reduce some of the La Nina variation from the time series in a simple way (and it’s also a Poincare map so it is probably one of the better simple ways). Given the denialist reaction to BEST as ‘proving’ that warming has stalled, it would would be a bit of a poser for denialists to explain why a simple temperature series hasn’t stalled. I understand it would be an inferior adjustment to the one for La Nina, volcanoes, etc. in the other thread. But this notion would fit on a bumper sticker.

    Comment by Andrew — 6 Dec 2011 @ 9:20 AM

  8. Can one plot the temperatures at the La Nina maxima for a long time? This would reduce some of the La Nina variation from the time series in a simple way (and it’s also a Poincare map so it is probably one of the better simple ways). The denialist reaction to BEST was that it ‘proved’ that warming has stalled; let the denialists explain why a simple temperature series hasn’t also stalled. I understand it would be an inferior adjustment to the one for La Nina, volcanoes, etc. in the other thread. But this notion would fit on a bumper sticker.

    (Sorry in case of multiple posts, the Captcha was resorting to Cyrillic text and I don’t have that keyboard; so I can’t tell if this has gone through.)

    Comment by Andrew — 6 Dec 2011 @ 9:22 AM

  9. Following DrTskoul’s comment, Tamino lists sites where the new result is already under attack. Are there others?

    Comment by Pete Dunkelberg — 6 Dec 2011 @ 9:31 AM

  10. @3. Straw man. Temperature also rose after recent ice age. LIA was a local not global phenomenon. Current studies are for global temperature trends.

    Comment by DrTskoul — 6 Dec 2011 @ 9:33 AM

  11. I’d like to offer the same comment and question here as I did on Tamino’s blog a few months ago.

    I have always been surprised that the satellite and surface thermometer-based series are so similar, because they measure different things over the oceans. The thermometer-based series is ocean water temperature, the satellite series is (I think) air temperature. My question is whether this difference accounts for the higher variance of the satellite series and its greater apparent sensitivity to El Nino.

    [Response: Actually, they measure different things everywhere. The satellite measure a weighted average of air temperatures over the lower 3-5 km of the atmosphere – with the weighting depending a little on the surface type. Weather stations and the data products generated from them generally measure the air temperature at 2 meters above the surface. Ocean measurements track the temperatures in the near surface layer (to about 5m depth). But while these are all different quantities, their variations are coherent (as you can see) – even if they aren’t identical. – gavin]

    Comment by Christopher Hogan — 6 Dec 2011 @ 10:09 AM

  12. This is really very poor and I’m surprised its not critiqued more honestly on the blog( if it’s promoting science rather than ‘the cause’).This is not news about the temperature record, its a new adjusted temperature index in keeping with Taminos original discussion,in the face of slowing warming

    http://tamino.wordpress.com/2011/01/20/how-fast-is-earth-warming/

    This is a much better discussion and a comparison with the first graph would be appropiate

    http://www.yaleclimatemediaforum.org/2011/02/global-temperature-in-2010-hottest-year/

    Comment by PKthinks — 6 Dec 2011 @ 10:36 AM

  13. IIUC, this paper suggests that satellites and surface records have different sensitivities to various transient forcings (ENSO, aerosols, TSI), but when you correct for those, they show almost identical warming.

    But I thought that the lower atmosphere was expected to warm faster than the surface (when comparing global, land+ocean trends). So is there a problem, or am I just confused?

    Comment by toto — 6 Dec 2011 @ 10:37 AM

  14. JamesA wrote: “The stock denier response is, ‘we never doubted that the world was warming, just what was causing it’. “

    In my experience, it is quite common for deniers to claim both that the Earth is not warming and that the Earth is warming but not because of anthropogenic emissions, at the same time (eg. in the same blog comment).

    Most of them are just regurgitating talking points that have been spoon-fed to them, with no regard for whether any of it is true or even makes sense.

    Comment by SecularAnimist — 6 Dec 2011 @ 11:02 AM

  15. Thanks to the moderators for this.

    I think that short commentaries like this on recent climate science papers and reports that are “in the news” are very valuable to your readers, and hopefully don’t take as much time and effort as the longer, in-depth analyses of studies that you do so well. If you can do more of these, that would be great.

    Comment by SecularAnimist — 6 Dec 2011 @ 11:05 AM

  16. Hardy Cross @3

    Curious. Don’t we all agree that temps have risen globally since the LIA? Why is this new study needed?

    anticipated JamesA @4

    The stock denier response is, “we never doubted that the world was warming, just what was causing it”.

    JamesA’s point couldn’t be more neatly proven …

    Comment by dhogaza — 6 Dec 2011 @ 11:06 AM

  17. Gavin, thank you for the response. This is just idle curiosity on my part (so not asking for further response), yet I’d like one chance to rephrase my question in the form of an assertion.

    This paper reconciles the trends nicely. It would be icing on the cake to pin down the reasons for differences in variance. And if that could be attributed to some physical basis, that would provide a stronger rationale for different adjustments to the series, beyond best statistical fit.

    Now realizing the series are different everywhere, one significant difference is that the satellite series capture air temperatures, the ground based series are ~70% water temperatures. Naively I’d expect the thermal mass of the water to dampen transient temperature changes. So I’m guessing that might be the source of the greater apparent sensitivity of the satellite-based series. I was thinking crudely of splitting the data into land and ocean observations and seeing whether the variances were more nearly equal over land. Alternatively, I might ask whether GCMs predict different sensitivities (e.g., to El Nino years) for near-surface air temperatures versus surface water temperatures. If any of the above panned out, I’d consider that some physical justification for making larger adjustments to the satellite data. On top of the evident statistical justification.

    Comment by Christopher Hogan — 6 Dec 2011 @ 11:15 AM

  18. This surely does not impress anyone? cherry pick the internal/natural variability with a negative trend and then argue that 2010 is significantly warmer than the rest of the decade??

    This is a much better discussion and withouth the ridiculous scaling of the axes

    http://www.yaleclimatemediaforum.org/2011/02/global-temperature-in-2010-hottest-year/

    This has been a meme on Taminos blog for a long time

    http://tamino.wordpress.com/2011/01/20/how-fast-is-earth-warming/

    There was a very good post on real climate

    http://www.realclimate.org/index.php/archives/2008/05/what-the-ipcc-models-really-say/

    including a discussion of what would be an unambiguous new annual temperature record in the context of evolution of a warming planet and we havent had one yet

    Comment by PKthinks — 6 Dec 2011 @ 12:03 PM

  19. Why do the 1997-98 El Nino and the 2007-09 La Nina still show up prominently in the filtered data? Is this the result of different sensitivity of the satellite data to ENSO variations?

    Comment by mark48 — 6 Dec 2011 @ 12:12 PM

  20. Texas is certainly the exception to 2011 being a cool year!

    Seems to me the past La Niña induced drought and high temperatures in Texas were about as horrible as ever experienced
    in the last hundred years or so. Texas fires were pretty scary in some places. Eastern US coastal storms last summer weren’t too shabby either.

    “In a year of hot and dry extremes, the state of Texas officially notched another record this week. The National Climatic Data Center reported that Texas had an average temperature this summer of 86.8 degrees.
    “That blew away the previous record for the warmest summer by any U.S. state on record, set by Oklahoma in 1934 with an average temperature of 85.3 degrees. “Oklahoma set that record during the heart of the Dust Bowl.”
    La Niña’s return may extend Texas drought

    Then:

    EL NIÑO/SOUTHERN OSCILLATION (ENSO) DIAGNOSTIC DISCUSSION EL NIÑO/SOUTHERN OSCILLATION (ENSO) DIAGNOSTIC DISCUSSION

    “During November 2011-January 2012, there is an increased chance of above-average temperatures across the south-central U.S. with the odds favoring below-average temperatures over the north-central U.S.  Also, above-average precipitation is favored across the northern tier of states, excluding New England, and drier-than-average conditions are more probable across the southern tier of the U.S. (see 3-month seasonal outlook released on 20 October 2011).”

    We expected more of the same this fall/winter as the La Niña weather pattern continues.

    But as it continues it’s started raining in Texas, especially this past November and into December. Hot and dry, now cold and rainy as the La Niña presses on. What gives? Does anyone know what to expect?

    Comment by Tim Jones — 6 Dec 2011 @ 12:26 PM

  21. ref: comment 1
    “We need to get on the game and counter the deniers…”

    Seems to me the effort is meaningless unless we counter the spineless, unprincipled pols we think are on our side.
    Quote:
    Analyst Blasts U.S. Negotiator at Climate Talks: Warns of “Eco-Apartheid”

    MICHAEL DORSEY, michael.dorsey@dartmouth.edu. “The arrival of lead U.S. negotiator for the United States, Todd Stern, in Durban South Africa spells doom for Africa and the planet,” said Dartmouth College Professor Michael Dorsey, after leaving a closed briefing with U.S. Special Envoy for Climate Change Stern and the U.S. Deputy Special Envoy for Climate Change Johnathan Pershing.

    “The lack of any form of visionary leadership on display was startling.” added Dorsey. “The U.S. government is no longer committed to doing just nothing. Worse than nothing, the U.S. plans to assess its performance in 2015 and maybe consider action in 2020. Such diplomatic delays are a deadly formula that will drive the displacement, wreak havoc, especially on African and other marginalized livelihoods globally. The UN’s latest estimate is that more than 150 million people could become early climate refugees. These people will be early victims of worsening and unfolding climate chaos if countries wait to consider to act until 2015.

    “Because of the U.S.’s expressed commitment to delays, the world may indeed see the Durban Climate Summit as the place where a new form of climate injustice and apartheid began: Eco-apartheid against those on the margins of society and ecosystems.”

    Comment by Tim Jones — 6 Dec 2011 @ 1:19 PM

  22. Please note corrections to the links in my first comment:

    La Niña’s return may extend Texas drought

    and

    EL NIÑO/SOUTHERN OSCILLATION (ENSO) DIAGNOSTIC DISCUSSION EL NIÑO/SOUTHERN OSCILLATION (ENSO) DIAGNOSTIC DISCUSSION

    Comment by Tim Jones — 6 Dec 2011 @ 2:24 PM

  23. It could be quite useful to give some statistical data for data sets such as this one. For example, what is the correlation coefficient (r-squared)? To the eye it looks very high.

    Comment by David Beach — 6 Dec 2011 @ 2:26 PM

  24. #16–I don’t have time to deal with all the dubious presumptions made in this comment, but India is a long way behind the US as a CO2 emitter; it just last year edged past Russia for the #3 spot. So point #1 is wrong, as is the statement at the end about ‘the two biggest emitters.’

    Comment by Kevin McKinney — 6 Dec 2011 @ 2:35 PM

  25. Drat. The first link works in the preview but not in the posted comment #18. Work now? Please replace in situ and not tax folks by repeating two admin comments.

    La Niña’s return may extend Texas drought

    Comment by Tim Jones — 6 Dec 2011 @ 2:39 PM

  26. @15 Christopher Hogan

    The larger variability in the tropospheric series is largely driven by the tropics. Here, the climate system is driven by convective processes. At the surface the energy is partitioned between latent (moist) and sensible (dry) heating. On convection clouds form and the latent (moist) energy is converted to sensible heat upon condensation. So, it follows on phtysical grounds that any temperature change at the surface gets amplified aloft which means that the variability in temperature (solely the ‘dry’ energy term) is larger aloft than at the surface. This has been documented since (at least) the very earliest model papers by Manabe and colleagues and in the observations since at least a 1994 paper by Christy and McNider in Nature. This won’t apply elsewhere where different processes are at play in addition but the tropics are such a large areal proportion of the globe that this in large parts explains the variance disconnect. It also doesn’t necessarilly follow (guessing the next argument someone will raise here …) that global trends should be greater in the troposphere than at the surface although in the tropics this should be the case (the ‘hot spot’, except if the surface were cooling instead it would be the ‘cool spot’ which sounds much less exciting).

    Comment by Peter Thorne — 6 Dec 2011 @ 2:40 PM

  27. PKthinks said:”This surely does not impress anyone? cherry pick the internal/natural variability with a negative trend and then argue that 2010 is significantly warmer than the rest of the decade??”

    Variability has no trend. For variability on a long time scale, the effect is generally constant over a short time period (such as Milankovitch cycles). For a very short time scale (such as ENSO) variablility averages out over decades.

    Specifically, tamino addressed 3 sources of variability:
    1) ENSO, short term 2-3 years, averages out, removing it removes most of the noise
    2) solar, 11 year, but roughly sinusoidal and well characterized, easily removed for that reason
    3) volcano, episodic, no characteristic time period. Fairly well characterized by aerosol index, with short term, very large effects, easily removed from a steady underlying trend

    PKthinks further said:”This is a much better discussion and withouth the ridiculous scaling of the axes

    http://www.yaleclimatemediaforum.org/2011/02/global-temperature-in-2010-hottest-year/

    The link is about something else. Your question and assertion do not impress me.

    Comment by t_p_hamilton — 6 Dec 2011 @ 2:43 PM

  28. First, thanks to everyone at realclimate for all their excellent work; this website goes a long way to help negate the impact of the mostly fossil fuel funded denier charade, and is especially useful for the interested layperson to stay abreast of current research on global warming. Just wondering if anyone here could point me to any studies of climate projections over the coming 2 to 5 decades, for specific regions e.g. I am in Basel, Switzerland. Selfish I know, but I ask as we have had some really quite bizarre weather over the last couple of years and notwithstanding the fact that no specific weather event can be attributed to global warming, I am wondering how this might potentially develop over the coming years. I fully realise that most studies cover much longer periods/further out e.g. 2050, 2100, 2300 and that shorter term predictions are much more error prone than longer term ones.

    Comment by Karl Curtis — 6 Dec 2011 @ 2:47 PM

  29. timg56’s post doesn’t even pretend to be on-topic.

    Please, let’s not let this thread be diverted this way. There’s an “unforced variations” thread for a reason.

    [Response: Yes, thanks; I just moved it and all responses to it.–Jim]

    Comment by dhogaza — 6 Dec 2011 @ 4:13 PM

  30. PKthink’s posts seem borehole-worthy as well …

    Comment by dhogaza — 6 Dec 2011 @ 4:17 PM

  31. You guys all know what the response from the dark side is going to be…

    “This is final proof that scientists are fudging the data! Conspiracy!”

    Comment by Ole — 6 Dec 2011 @ 4:41 PM

  32. “This surely does not impress anyone? cherry pick the internal/natural variability with a negative trend and then argue that 2010 is significantly warmer than the rest of the decade??”

    Yes, because using the entire length of the satellite record is ‘cherry picking’.

    Do you have a coherent criticism to make?

    Comment by MartinM — 6 Dec 2011 @ 4:54 PM

  33. My #21 refers not to the present #16, but to #144 on the Unforced Variations thread, should anyone actually care. (UV #144 was moved from this thread as OT here.)

    Comment by Kevin McKinney — 6 Dec 2011 @ 5:20 PM

  34. How credible is the result obtained by exclusion of ‘natural’ events when is not exactly clear what is contribution of these events?
    Just to contrast with above 60 year record, here is a 6 times longer one:
    http://www.vukcevic.talktalk.net/SSN-T.htm and its derivative http://www.vukcevic.talktalk.net/HMF-T.htm
    (data sources made available to solar scientist Dr. Svalgard of Stanford and climate scientist Dr. Steig of Washington universities).
    I ask the authors (Grant Foster and Stefan Rahmstorf) what might be left if just the solar cycle is excluded?
    I propose that the climate science is still not matured to the degree where it can judge total effect of any of the exclusions: it follows that credibility of above can and will be successively challenged, not by myself (lacking adequate competency ), the sceptics, the deniers, etc., but followers of what the science should be, independent unbiased and fully credible.

    Comment by vukcevic — 6 Dec 2011 @ 5:38 PM

  35. Martin, I can’t figure out what “PKthinks” meant either time; he posted two versions complaining about scaling. I thought he might be unhappy to see:
    — the adjustment (in the new paper) losing the 1998 RSS high temp shown in Zeke Hausfather’s older graph, so the “cooling trend” argument gets hurt, or
    — the newer graph having one more recent data point than the older, so the “cooling trend” argument gets hurt, or
    — the newer graph showing a shorter time span and so not showing the lower temps in earlier decades, so the “cooling trend” argument gets hurt, or
    — the newer graph isn’t directly comparable to an older graph he prefers to look at without thinking about the numbers along the side, or
    — I dunno.

    PKt, you should look at the charts at http://www.globalwarmingart.com/wiki/Temperature_Gallery — now sadly out of date, but the point is, you won’t find all temperature graphs done to exactly the same scale; you can’t just compare the pictures without reading the captions.

    Comment by Hank Roberts — 6 Dec 2011 @ 5:38 PM

  36. #16 ‘Variability has no trend’
    almost an oxymoron this one.. of course it has in the short term!
    internal/natural variability over a long enough timeframe will not alter the long term trend of the temperature record(as we are always reminded) but in this relatively short term analysis it did especially for the last decade

    Comment by PKthinks — 6 Dec 2011 @ 5:40 PM

  37. note to mod: typo ‘6 times’ should be ‘5 times’

    Comment by vukcevic — 6 Dec 2011 @ 5:43 PM

  38. “internal/natural variability over a long enough timeframe will not alter the long term trend of the temperature record(as we are always reminded) but in this relatively short term analysis it did especially for the last decade”

    Well, yes. That’s kind of the point. Internal variability sometimes masks the underlying forced trend, and so stripping away that variability reveals the trend.

    Comment by MartinM — 6 Dec 2011 @ 6:19 PM

  39. PKthinks, I think I get your point. You’re saying “the last 10 years show just as much warming as the prior 20 in the Foster analysis, but the last ten years don’t show quite as much warming when you don’t remove the short term variability factors (ENSO, aerosol, solar). Therefore those short term factors are what has affected the last ten years, causing the nonsignificant apparent 10 year decrease in the magnitude of the overall 30 year warming trend. Is that your point? If so, I think you are in agreement with the paper…

    Comment by Utahn — 6 Dec 2011 @ 7:04 PM

  40. #36–Variability must be calculated over a given period, and it describes that period as a whole. So for a given period, no trend.

    If you want to characterize changes in variability, you compare different periods, as Hansen et al 2011 did:

    http://www.columbia.edu/~jeh1/mailings/2011/20111110_NewClimateDice.pdf

    Or so I understand it; the more statistically-literate will no doubt correct me if I’m wrong.

    Comment by Kevin McKinney — 6 Dec 2011 @ 7:15 PM

  41. If so, I think you are in agreement with the paper…

    He seems to be saying that it’s unfair to strip out known factors that impact natural variability.

    In other words, one should …

    hide the incline.

    Comment by dhogaza — 6 Dec 2011 @ 7:25 PM

  42. “This is a much better discussion and a comparison with the first graph would be appropiate ”

    The discussion by Zeke isn’t really on the same topic. This paper is about estimating natural variability then subtracting it from the original to reveal the underlying trend not accounted for by known natural causes. If you think the analysis is poor, then can you what part of analysis is at fault and why?

    Comment by Phil Scadden — 6 Dec 2011 @ 7:39 PM

  43. Can anybody refer to a paper that clearly describes to what extent the ENSO variability actually relates to changes in the total thermal energy of the system (oceans+air), and to what extent it’s just heat being shuffled around within the system from one place to another? To the extent the models have something approaching ENSO-like behaviour, it’d be interesting just to know what the models do, in that regard.

    Comment by tharanga — 6 Dec 2011 @ 8:11 PM

  44. > of course it has in the short term!

    Not _detectable_ statistically.

    Shorten the span of years or number of observations to fewer than enough

    (meaning enough to do the statistical arithmetic; enough is how many data points are going to be needed, based on how much the numbers in that particular data set jumped around as you collected them.)

    (You can’t just start and go on collecting data points until you see a detectable trend and declare you know something for sure, that doesn’t work.)

    Of course “it’s there” in retrospect in the sense that you can draw a line between the end points on the paper.

    The likelihood is what you’re testing statistically.
    That’s that gray fuzz around the crisp clear lines on the charts — the shorter the span of years, the fuzzier the picture. There’s no _detecting_ whether or not there’s any trend, when you do the numbers on short time spans or small numbers of observations.

    Comment by Hank Roberts — 6 Dec 2011 @ 8:33 PM

  45. ENSO just causes redistribution of heat. It is not a heat generator or heat sink.

    Comment by DrTskoul — 6 Dec 2011 @ 9:20 PM

  46. PKthinks,

    As the author of the piece that you link, they are really about two quite different things. Foster and Rahmstorf are trying to create a record where short-term (ENSO, solar) and stochastic (volcanoes) variability are removed. My article pointed out that even if these are not removed, the 2000-2010 temperatures are (slightly) warmer than we would expect if the 1979-2000 linear trend was used as a predictor. While there is certainly some grounds to disagree with the specific choices used to adjust the temperature record by Foster and Rahmstorf, and I wouldn’t expect it to replace the standard GISTemp/NCDC/Hadley products any time soon, its quite an interesting exercise and a useful contribution to the literature.

    Comment by Zeke Hausfather — 6 Dec 2011 @ 9:53 PM

  47. #46 ZH I am merely pointing out that your commentary on the temperature record points out that 2010 is not significantly warmer and is not an unamgiguous new record in the last decade,
    whereas the Foster and Rahmstorf while admitting their analysis shows
    ‘no sign of a change in the warming rate during the period of common coverage’

    are very happy to use the graphical appearance of their analyis to suggest significant new record temperatures. So in the short term you make the warming of the last decade apparrently more significant. If you set out with that intention thats not very difficult, its not that he(they) havebt been pushing that idea prior to submitting the paper and if you consider it a good contribution I am surprised.

    Comment by PKthinks — 7 Dec 2011 @ 3:30 AM

  48. What’s interesting to me is the linearity of the results using just solar variability, ENSO, and volcanoes. Does this study suggest that there are no long-term cycles of any significance?

    I also wonder what happened in 1981-2-3. What caused the gyration in all the data sets?

    Comment by RichardC — 7 Dec 2011 @ 5:00 AM

  49. #45–“ENSO just causes redistribution of heat. It is not a heat generator or heat sink.”

    Basically true, in the sense that ENSO redistributes heat much more than anything else.

    However, there is some effect on OLR, since ENSO does affect global mean temperature, which in turn determines mean radiative efficacy: the planet radiates a bit more during the warm El Nino phases and a bit less during the cool La Nina phases.

    Comment by Kevin McKinney — 7 Dec 2011 @ 7:21 AM

  50. This reconstruction simply confirms Arctic events so massive and undeniable. there is no question about warming, none. Obstructionists offer weak doubts in comparison,
    compare their vile swipes against reality with small Arctic glaciers disappearing since 2006 http://eh2r.blogspot.com/ .. Also the cooling stratosphere is really occurring at the same time as these vanishing glaciers. Again vindication for ever so improving GCM’s.

    Comment by wayne davidson — 7 Dec 2011 @ 8:49 AM

  51. Richard C,

    I don’t think the study says anything about long-term cycles. The reference period is only ~30 years so any longer term effects will simply be part of the apparent trend.

    There was a large volcanic episode in early-1982 followed by an extreme El Nino in 1983 (comparable to 1998). I imagine these large overlapping competing factors, at that point and elsewhere, played havoc with calibration of the model which leaves the adjustments being useful but less than perfect.

    Comment by Paul S — 7 Dec 2011 @ 9:26 AM

  52. RichardC,
    Depends on what you mean by “long-term” here. Have you heard of Milankovitch Cycles?

    Comment by Mark Schaffer — 7 Dec 2011 @ 9:28 AM

  53. @10 – No global LIA? Surely you jest?

    climate.envsci.rutgers.edu/pdf/FreeRobock1999JD900233.pdf

    Comment by Veritas — 7 Dec 2011 @ 9:29 AM

  54. RichardC asks:”What’s interesting to me is the linearity of the results using just solar variability, ENSO, and volcanoes. Does this study suggest that there are no long-term cycles of any significance?”

    Pretty much, for a 30 year period. There may be some cycles on decades or century timescales, but with low amplitude (i.e. significant impact). Longer term cycles would be too slowly changing over 30 years.

    I also wonder what happened in 1981-2-3. What caused the gyration in all the data sets?”

    Mt. Pinatubo.

    Comment by t_p_hamilton — 7 Dec 2011 @ 9:41 AM

  55. I am merely pointing out that your commentary on the temperature record points out that 2010 is not significantly warmer and is not an unamgiguous new record in the last decade,
    whereas the Foster and Rahmstorf while admitting their analysis shows
    ‘no sign of a change in the warming rate during the period of common coverage’

    are very happy to use the graphical appearance of their analyis to suggest significant new record temperatures.

    You’re pointing out that analyses of different things show different things? OK, then. That wouldn’t seem to justify your insinuation that there’s something untoward about the Foster and Rahmstorf analysis. It’s almost as if you don’t have anything of substance to say.

    Comment by MartinM — 7 Dec 2011 @ 10:09 AM

  56. PKT, short time spans don’t allow detection of a trend.

    You don’t like the picture.

    That doesn’t mean the authors are trying to fool you with it.

    You don’t like seeing the pointy bit on the right higher than the flattish bits on the left. OK, we get that.

    You think the whole line looks too steep.
    You found a less steep one in Zeke’s article — OK, we get it.

    But you’re fooling yourself focusing on the appearance of the picture while ignoring the data behind the chart.

    You can’t understand climate just looking at pictures of charts.
    Yes, people can be fooled by them. We know that. But — you can’t force all the charts to use the same scale or time span. They’re _pictures_ of data.

    Take any climate science question. Test it for yourself.
    Put it into Google, then into Scholar, then into Google Images.

    Google gets you a dog’s breakfast of information.
    Scholar gets you mostly science, with a smattering of, er, other stuff.

    Image search gets you — invariably — mostly denial/PR blogs.

    Why?

    The pictures impress people who don’t understand the arithmetic.
    OK. That’s your point, we get that. But you can’t fix the _pictures_.

    People who point to pictures _without_ explaining them can’t be trusted.

    Don’t assume you know the motivations of the authors.
    Read the text. Read the captions.

    You’re arguing against a picture because you don’t like the picture.
    Instead, try to understand it.

    Comment by Hank Roberts — 7 Dec 2011 @ 10:29 AM

  57. I’m writing today as less of a comment and more of a call for help. I have a very strong science background (mostly in the biological sciences) but I have to admit I’m very much lacking knowledge in climate science. So much so that I don’t even feel comfortable commenting on it.

    I’ll turn myself over to you experts. Can you all recommend any good sites where I can learn the truth from the ground up? I have a science based website and I’m sure the topic will come up some day.

    Thanks in advance for your assistance.

    –Guy McCardle
    The Inconvenient Truth

    Comment by Guy McCardle — 7 Dec 2011 @ 4:21 PM

  58. As I said at Tamino’s blog, I have done a very similar analysis (but far less sophisticated) to that in Foster/Rahmstorf using nothing but Excel and manually tuning the magnitude and lag of the ENSO, AOD, and solar forcings. It’s quite easy to do, and while it isn’t worthy of publication by any means, anyone with Excel and a small amount of statistical knowledge can verify Foster & Rahmstorf’s basic conclusions for themselves.

    In fact, the more I think about it, the more I think that doing the basic analysis is so easy that it ought to be required of anyone who wants to be taken seriously in a discussion of climate in which math, data, and science are involved. I don’t know how anyone could comes away from their own analysis still thinking “it’s all natural variability” or anything similar. And these days, nearly everyone’s got Excel or something similar.

    Comment by Brian Angliss — 7 Dec 2011 @ 4:58 PM

  59. LIA was mostly a European and possibly a northen hemisphere cooling. The notion of sychronous global cooling during LIA has been dismissed ( Bradley & Jones 1993, Jones at al. 1998, Mann 1999 etc. etc.)

    Comment by DrTskoul — 7 Dec 2011 @ 5:22 PM

  60. PKthinks, to paraphrase Crocodile Dundee: *that’s* not scaling axes, *this* is:

    Denial Depot takes on arctic sea ice extent

    (too bad that site’s gone a bit stale. The post complaining about the thickness of pencils used to draw graphs was priceless)

    Comment by Steve Metzler — 7 Dec 2011 @ 5:49 PM

  61. Guy McCardle @57 — There is the start here at the top of the page. That will, in part, direct you to “The Discovery of Global Warming” by Spencer Weart which is also linked (first) in the science section of the sidebar.

    Comment by David B. Benson — 7 Dec 2011 @ 7:06 PM

  62. @ Guy McCardle

    In addition to the sage advice from David B. Benson above, I also suggest that interested people go to Skeptical Science for over 4,700 different threads discussing the various nuts&bolts (and controversies) of climate science. There is an immense amount of reference material discussed there and it can be a bit difficult at first to find an answer to your questions. That’s why it’s recommended to peruse the Newcomers, Start Here thread first followed by The Big Picture thread.

    I also recommend watching this video on why CO2 is the biggest climate control knob in Earth’s history.

    Further general questions can usually be be answered by first using the Search function in the upper left of every Skeptical Science page to see if there is already a post on it (odds are, there is). If you still have questions, use the Search function located in the upper left of every page here at Skeptical Science and post your question on the most pertinent thread.

    Remember to frame your questions in compliance with the Comments Policy and lastly, to use the Preview function below the comment box to ensure that any html tags you’re using work properly.

    Comment by Daniel Bailey — 7 Dec 2011 @ 10:59 PM

  63. Guy (#57)

    Depends on what you want to learn. If you’re looking for general assessments of climate change, the IPCC 2007 report is probably the most comprehensive single source, and while there’s been good progress since then on a number of topics, not thehing in “big picture” has really changed. The National Academies also has several online reports on the subject, as does USCCP, depending on your interests (the recent 2010 Climate Stabilization report is a great read).

    For a more general climate physics background, textbooks are probably the only good route. “Global Warming: The Complete Briefing” by Houghton, as well as David Archer’s “Understanding the Forecast” are great as a qualitative (or some algebra at the most) based introduction that covers many of the big topics needed to start discussing the issue. These might actually be something good to read before the IPCC report.

    For more climate physics, Dennis Hartmann’s is good, less based on climate change than climate dynamics in general, and a bit more mathematically rigorous. Ray Pierrehumbert’s is one of the more thorough, although might have a lot of information you’re not interested in, and while it gives you all the tools to think about climate change, is not a “climate change” book per se.

    Comment by Chris Colose — 7 Dec 2011 @ 11:04 PM

  64. First paragraph– “…nothing in the “big picture” has really changed”

    Comment by Chris Colose — 7 Dec 2011 @ 11:05 PM

  65. Guy McCardle @ 57, by all means start with Spencer Weart as recommended. You can order the book right now. It doesn’t cost much. I think all the contents are also online but it is best to read an actual book offline for some longer things (not too long in this case).

    While waiting for the book to arrive you can start learning about Fourier, de Saussure and others:
    http://hubpages.com/hub/The-Science-Of-Global-Warming-In-The-Age-Of-Napoleon

    http://hubpages.com/hub/Global-Warming-Science-In-The-Age-Of-Queen-Victoria

    http://media.wiley.com/product_data/excerpt/73/14051961/1405196173-38.pdf
    http://geosci.uchicago.edu/~rtp1/papers/NatureFourier.pdf

    By and by plan on learning the Stefan-Boltzman law (with a consequence often referred to as the Planck feedback) and the “bare rock approximation.”
    On grasping that our environment is much warmer than the bare rock approximation you will not be mystified that global warming occurs….

    After a planet’s basic heat balance, planetary physics is also about all the consequences of the constant energy flux through the environment. Then there is paleoclimatology and more.

    Comment by Pete Dunkelberg — 7 Dec 2011 @ 11:18 PM

  66. #60 SM very good, I still think F+R win that prize

    Comment by PKthinks — 8 Dec 2011 @ 4:30 AM

  67. #65–

    Thanks for linking those, Pete.

    Also, and a tad less familiarly–a (fairly) quick historical survey of the observational study of radiation in and above the atmosphere–or at least a few of its high points:

    http://doc-snow.hubpages.com/hub/Fire-From-Heaven-Climate-Science-And-The-Element-Of-Life-Part-One-Fire-By-Day

    http://doc-snow.hubpages.com/hub/Fire-From-Heaven-Climate-Science-And-The-Element-Of-Life-Part-Two-The-Cloud-By-Night

    Comment by Kevin McKinney — 8 Dec 2011 @ 2:27 PM

  68. SM very good, I still think F+R win that prize

    Perhaps you could articulate a coherent reason for thinking that.

    Comment by MartinM — 8 Dec 2011 @ 2:39 PM

  69. Guy McCardle, if you are still “here”, I’m going to partly disagree with Chris Colose. This would generally be considered absurd since he is way ahead of me in climatology, but of course you will know what works for you.

    If you start with Skeptical Science (which is greatly appreciated by the reality oriented community) what you find is one argument after another after another with no end in sight. On the other hand if you start with fundamental science then the argument over the big picture ended some time in the past. Chris probably agrees and was too modest to mention this.

    Skeptical Science example: in one of their recent posts they counter someone who has a convoluted argument that sea level is not rising. Well, is it or isn’t it?

    First, as a known physical fact it is.
    Second, there are basic physical reasons like conservation of matter that make it rise.
    1) thermal expansion of the oceans: measured ocean heat content keeps increasing and this causes the ocean to expand.
    2) loss of land based ice: both land based observations (Glacier National Park for instance) and satellite gravity measurements make it clear that land based ice is decreasing.

    So where is the water? Is it in the air? In a warmer world there is more evaporation (and precipitation) and more water is in the air. I have seen this estimated as about the volume of Lake Superior so far. This is no match for 1 and 2 above. Is it in the earth? In fact when there is a year of heavy flooding, drainage can’t keep up and sea level drops, but this variation is superimposed on the long term trend of rising seas. Over long time periods the amount of water within the earth’s crust can vary, but we are depleting aquifers (partly countered by building reservoirs). So by conservation of water, sea level must be rising. Of course scientists check and check and compare measurements against each other. But they don’t really suspect water is vanishing from the planet and neither should you.

    In short: I suggest getting a handle on the physical basics, and linking people to sites like Skeptical Science if they insist on arguing. At least initially, and permanently for most people, all the details at Skeptical Science (eg of individual arguments against physical realities) are a distraction. It is nevertheless very valuable to have a site like Skeptical Science on hand.

    Comment by Pete Dunkelberg — 8 Dec 2011 @ 3:00 PM

  70. Looking at the bottom graph, or perhaps in general. Shouldn’t one say “in a time-scale DOMINATED by non-La Nina episodes, La Nina seems to not be very influential”? Although I like how you frame this otherwise from your point of view, I think the above statement would be more correct, no?

    Comment by Bokonon — 8 Dec 2011 @ 4:04 PM

  71. Guy @ 57 (climatology resources)

    I’ll weigh in on this a bit. You asked specifically for “sites” – I presuming that you want something you can read on the web. I strongly suggest that you consider other sources, particularly in the form of textbooks for undergraduate (or perhaps graduate) university courses. What university or college libraries are close at hand? Or a university bookstore? Nearly any introductory physical geography text will have a decent section on descriptive climatology, and this will be a starting point for the basics. (The only exception I can think of offhand would be the one that has Tim Ball as a co-author.) If you can’t sign the books out, one of these would probably make an easy afternoon’s quick read in the library, based on your description of your science background. Don’t expect there to be much math – but that will make it easy to get your head around the basic concepts.

    Next step would be to peruse the library stacks for more advanced undergraduate texts. I used to use Henderson-Sellers and Robinson’s “Contemporary Climatology” – back when it was in a first edition. I see it’s now in a second edition, but even that is only from 1999. Expect some more math and detail, but still a fairly easy read. Not an afternoon, but a couple of weekends might do. There are probably lots of similar books (a search for “climatology” at Amazon yields over 8,000 books), and going with what is available locally is simplest. Again, if you don’t have borrowing rights at the local U, try an interlibrary loan through a municipal library. Or, if they have a decent book in the local university bookstore, you may want to buy yourself a copy. Now may be a good time if they are bringing in texts for the second term. [Side note: they still do use textbooks at universities, don’t they??? Jeez, I feel old…]

    When I was an undergrad, we used Sellers “Physical Climatology”. That’s clearly dated now (printed in the 1960s), but is a classic. Covers earth-sun relationships, radiation and energy balances, microclimatology, and includes some math. Shows up for $7.98 (used) on Amazon. I’ve also heard that Hidore’s book is not too bad, but I have no direct experience with it. It’s the first hit in Amazon’s “climatology” search.

    Once you get going with some basics, you can focus in on which part of the subject you want to learn more about. At that point, come back here with a description of what you have learned and what you want to learn, and get more suggestions. If you start with something too specific or advanced, you’ll find that sources may assume more than you already know.

    …and as things progress, come back and post and tell us what you’ve done and how things are going…

    Comment by Bob Loblaw — 8 Dec 2011 @ 4:27 PM

  72. A plea:

    The picture at the top — used to illustrate the original post — is a composite, without spaces between the pieces, and if you just look at the picture without finding the description, you’ll boggle when you read the numbers along the Y axis.

    It’s a composite of four different charts — with overlapping temperature span — but the four are stacked so it looks like one big X/Y chart.

    I know, “don’t do that” — but a lot of visitors you might think of as ‘readers’ are in practice ‘viewers’ — so better pictures would better serve those who come here to look and go away after looking.)

    All the originals are available where that comes from.

    Any chance someone with a connection to the work could do a graphic illustration that works for this?

    Pick pictures and write simple captions to explain what’s being published?

    http://www.pmodwrc.ch/tsi/composite/pics/

    Comment by Hank Roberts — 8 Dec 2011 @ 5:54 PM

  73. Thanks so much to everyone who gave me advice on how to get educated about climate science. I know I said sites, but I’ll be reading good old fashioned books as well. Someone asked what colleges/universities I live near. Fortunately I live fairly close to Penn State University. They have a good meteorology program. I even used to read forcasts for Accu-Weather in State College a long time ago….but I digress.

    I’m ready to dig in and learn. You guys have all been nice and very helpful. Thanks again.

    –Guy
    The Inconvenient Truth

    Comment by Guy McCardle — 8 Dec 2011 @ 6:37 PM

  74. 54 t_p_hamilton,

    Pinatubo erupted in 1991. Did you mean El Chichón, which erupted in 1982?

    Comment by TrueSceptic — 8 Dec 2011 @ 7:38 PM

  75. I think this is neat, that is Foster and Rahmstorf.

    Does anyone know what causes the few large fluctuations that remain, e.g. 1982, 1983, 1984? I’m guessing “no” or else it would have been removed.

    Is there an implicit or explicit claim that this linear trend (plus identifiable disturbances) will continue into the future? Can you decompose this into a part due to CO2 and a part due to whatever produced the rest of the increase since the 19th century?

    Comment by Septic Matthew — 8 Dec 2011 @ 7:58 PM

  76. 51, Paul S: There was a large volcanic episode in early-1982 followed by an extreme El Nino in 1983 (comparable to 1998). I imagine these large overlapping competing factors, at that point and elsewhere, played havoc with calibration of the model which leaves the adjustments being useful but less than perfect.

    Anyone else have an idea?

    Comment by Septic Matthew — 8 Dec 2011 @ 8:04 PM

  77. Foster and Rahmstorf (Figure 7) display the estimates of the effects of the MEI, AOD and TSI, but not the MEI, AOD, and TSI themselves, so you can’t determine from their paper whether a misfit to one or more of them is responsible for the swings that remain.

    I don’t mean that as a criticism: I like what they did.

    Comment by Septic Matthew — 8 Dec 2011 @ 8:28 PM

  78. SM, in the paper you’re not-criticizing you say they did not include in the journal “the MEI, AOD, and TSI themselves, so you can’t determine from their paper ….”

    What field did say you’re in?
    How do they publish databases in your field?

    On page 2 you’ll find “Section 2. Data” listing how to get what you’re not-complaining about not-having.

    Comment by Hank Roberts — 8 Dec 2011 @ 9:06 PM

  79. Guy McCardle, the (somewhat long) lecture series of D. Archer is notably informative of the basics, you probably find much of this familiar, but assuming you’re a biologist or of the medical sciences, you may find much of it new or at least something not normally thought of. Starting at http://www.youtube.com/watch?v=uHXpkoE0G3A&feature=relmfu

    Comment by jyyh — 8 Dec 2011 @ 9:09 PM

  80. Also for SM — http://www.realclimate.org/index.php/data-sources/

    Comment by Hank Roberts — 8 Dec 2011 @ 10:00 PM

  81. 75. Septic,

    Tamino also tested an index based on pressure, but it didn’t change the results.

    Here’s a graph with all three components. There is a disparity between the El Nino index and smoothed temperature after large eruptions, as it should.

    Comment by apeescape — 8 Dec 2011 @ 10:26 PM

  82. #76 et seq–

    The principal author said that there should be residual effects remaining, since the correction factor is a single value, applied across the entire data set. Hence extremes–such as the 1998 El Nino, for example–will be under-corrected.

    The phrasing is mine, so any errors are not the fault of said author. . .

    Comment by Kevin McKinney — 8 Dec 2011 @ 11:40 PM

  83. 77, Hank Roberts,

    That was really only a minor comment about Figure 7 and the relevance to guesses above about the remaining swings in figure 5 reproduced above. I didn’t say the data were unavailable, only that the answer to the question (was it the El Chichon eruption in 1982?) isn’t in the paper.

    The links to the data sources, along with this and the Appendix permit someone to reproduce their procedure:
    In fact for some of the data sets, the annual cycle in temperature during the time span under analysis has changed noticeably relative to that during its baseline period. Hence there is a residual annual cycle. This is greater for the data sets whose baseline period is distinctly different from the time period analyzed in this study. For example, Fourier analysis of residuals from a linear fit to GISS data during the period January 1979–December 2010 shows clear peaks at
    frequencies 1 and 2 cycles yr􀀀1. To allow for a residual annual cycle in the data, we included in the multiple regression a second-order Fourier series fit to model an annual cycle, i.e., trigonometric functions with frequencies 1 and 2 yr􀀀1. This effectively transforms the adjusted data to anomalies with
    respect to the entire time span, by adjusting the annual cycle to match its average over that period. Therefore the multiple regression includes a linear time trend, MEI, AOD, TSI and a second-order Fourier series with period 1 yr.

    The influence of exogenous factors can have a delayed
    effect on global temperature. Therefore for each of the three factors we tested all lag values from 0 to 24 months, then selected the lag values which gave the best fit to the data.

    I don’t know why that goes in and out of italics.

    So, what do you think about the possibility that the El Chichon eruption was responsible for the residual big swing in 1982, 1983, 1984? Nothing?

    Comment by Septic Matthew — 9 Dec 2011 @ 12:43 AM

  84. 1980-1984? Doesn’t matter what I think, let’s look for some science. Well, where would you look?

    I tried http://scholar.google.com/scholar?q=1980-1984+climate+cooling

    From the first page, one paper looking at that span:
    Are global cloud albedo and climate controlled by marine phytoplankton?
    [PDF] SE Schwartz – Nature, 1988
    http://www.ecd.bnl.gov/steve/pubs/Nature1988MarinePhytoplank.pdf
    (Cited by 159 subsequent papers)

    Comment by Hank Roberts — 9 Dec 2011 @ 1:03 PM

  85. I like the way this reverses the rather bizarre logic of McLean et al 2009 who subtracted the linear trend then said, hey, presto, there’s only ENSO left. At least this is a real result, and one that includes some clear graphs that aid the nontechnical audience. Over here in COP-out-17 land, I’ve used this in what I hope is a clear presentation to the uninitiated. Comments and corrections there welcome.

    Comment by Philip Machanick — 9 Dec 2011 @ 1:47 PM

  86. One good leverage multiplier to have in ones logical toolkit when confronting deniers, is the very fact that those of us who had at least some education in geophysics of oceanography back in the 1970s’, all learned – and correctly so! – that the Earth was headed into another Great Ice Age!
    This may sound like giving support to the denialist brou-haa-haa, but it actually drives home the Fact that the Full Impact of Human Climate Modification is actually staving off that very Ice Age – providing, of course, that we don’t turn off the Atlantic Conveyor……..I hear there’s some nice towns in Uruguay where the people speak Norwegian…..
    Love Ya All.

    Comment by James Staples — 9 Dec 2011 @ 6:15 PM

  87. Congratulations on a fine research paper. I think its very important to try to reconcile and unify the models to get as much agreement as possible. Even though the adjustments may no turn out exactly right, it puts a stake in the ground to explain at least one way agreement could be reached.

    Comment by WebHubTelescope — 9 Dec 2011 @ 8:40 PM

  88. “I thought the 70’s-cooling mole had been well whacked, but no.”
    http://scienceblogs.com/stoat/2011/09/global_cooling_again.php

    Comment by Hank Roberts — 9 Dec 2011 @ 9:53 PM

  89. 84, Hank Roberts, you are correct: we should look at all omitted covariates; the paper only shows that the temperature series discrepancies can be reconciled, not that this is the correct or best way to do it. The authors used lagged versions of the regressor variables in their analysis, so in principal we should not ignore the possibility that the 1982-1983-1984 inflection was driven by an event that occurred in 1980.

    It’s still a good paper.

    Comment by Septic Matthew — 10 Dec 2011 @ 11:11 AM

  90. Very stark reading indeed. What I find very singificant is the CO2 concentration rate leading up to the last interglacial period. By using ice core analysis and other means we are certain that in the lead up 130KY ago CO2 was increasing at an average of 0.0001ppm/y. Wait for it!…we are currently pushing the rate at 2.0000ppm/y a 20000 fold increase. This rate must surely set a paleoclimatic record. We are definately in uncharted waters as even Prof. James Hansen would attest to. The big difference between the last intergalcial period and now is that now the air/ocean temp is rising year round forced inextricably by the relentless pressure of CO2. 130000 years ago it was the change in juxtaposition between the earth and the sun that caused the polar regions to heat up (still only by 0.7C warmer that today)and then that caused CO2 to increase. The situation now is the reverse of what is was then. We are literally in greenhouse conditions now and this is causing a 24/7/365 positive feedback juggernaut. In the last I.G.P flora and fauna at least has a fighting chance to adapt and evolve..not this time. A 20000 times faster onset now is a stupendously massive shock to the earth’s climate and it’s ecology. Personally I’m not sure how useful any future predictions of global climate based on the last IGP can be simply due to the unprecedented speed of today’s onset. Do known and well documented physical processes still operate and behave as they are supposed to under today’s rate of change?

    Comment by Lawrence Coleman — 11 Dec 2011 @ 2:05 AM

  91. Perhaps I missed it while reading the paper, or I am simply to dense to have understood, but how did the authors weight the different forcings in order to adjust the data? To put things in my own elementary banter: When the TSI, aerosols or ESNO effect increased, the temperature values in the raw data sets were decreased, in order to modulate correct for the bias caused from that particular forcing, correct?.. Were the data sets treated on an individualistic basis, as the algorithms used to correct the initial raw data were different?

    Comment by Badnon Hepekl — 12 Dec 2011 @ 9:36 PM

  92. Does this result suggest, since in the paper for the last decade stratospheric aerosols are low/flat, and since TSI is relatively flat and has small effect, that the recent fluctuation of global temperatures is mostly ENSO related?

    [Response: Short term (year-to-year) variability in global mean temperature is predominantly ENSO related at all times, and that impacts decadal trends as well. I don’t think that this is unique to this decade (though at each period the attribution would be a little different). – gavin]

    Comment by Utahn — 13 Dec 2011 @ 10:00 AM

  93. Thanks, I guess from all that people talk about the last decade I thought it would have been something more dramatic!

    Comment by Utahn — 13 Dec 2011 @ 11:35 AM

  94. Back when the seeds of this paper were being explored on Tamino’s ‘Open Mind’ blog I asked (under my pseudonym of ‘Ken Fabos’) –

    Just curious – of the (apparent) peaks and troughs that are left how much of that variation could reasonably end up suffering the same fate of being legitimately attributed to specific climate processes and phenomena and end up subtracted in a similar way to this to reveal, undisguised, the underlying trend?

    Tamino’s answer was he didn’t know but the question should be put to ‘genuine’ climate scientists. (As if his own contributions are mere adjunct to the work of others!).
    So, to the genuine climate scientists, looking at the peer-reviewed paper that resulted, is there an answer to that question?

    Comment by Ken Fabian — 13 Dec 2011 @ 2:03 PM

  95. [Response: Short term (year-to-year) variability in global mean temperature is predominantly ENSO related at all times, and that impacts decadal trends as well. I don’t think that this is unique to this decade (though at each period the attribution would be a little different). – gavin

    Is there an estimate of total variability which is attributed to the parameters, how much is likely other causes, and how much is likely error?

    And I kid you not, Captcha says “Richard otedxt”. I’ve never otedxted before.

    Comment by RichardC — 15 Dec 2011 @ 2:53 AM

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